As the Amazon rainforest disappears, rainfall falters over a much wider area

RAIN MAKER: Cutting down trees in the Amazon rainforest also reduces rainfall over the region. Image: flickr/Threat to Democracy

When Amazon rainforest disappears, so does Amazon rain.

That’s the conclusion of new research that shows deforestation can significantly reduce tropical rainfall far from the area where trees have been cut down.

That’s because air passing over forests picks up moisture given off by trees and plants, fueling rains. When those trees disappear, so does some of that rain.

“What we found was this really strong impact — air that traveled over a lot of forest brought a lot more rain than air that didn’t travel over very much forest,” said lead author Dominick Spracklen of the University of Leeds.

His research, published yesterday in the journal Nature, helps reconcile a situation that has puzzled scientists.

Climate models project that Amazon deforestation would reduce rainfall regionally. But limited observations show that rainfall in deforested areas is higher than in areas where the rainforest is still intact.

(Scientists believe that when trees are cut down, the bare surfaces left behind absorb more Read more…

RAINFOREST TO PASTURE: Deforestation, among other human impacts such as climate change, are having a rainforest-wide impact on the Amazon. Image: Courtesy of Compton Tucker, NASA GSFC

The Amazon rainforest is in flux, thanks to agricultural expansion and climate change. In other words, humans have “become important agents of disturbance in the Amazon Basin,” as an international consortium of scientists wrote in a review of the state of the science on the world’s largest rainforest published in Nature on January 19. (Scientific American is part of Nature Publishing Group.) The dry season is growing longer in areas where humans have been clearing the trees—as has water discharge from Amazon River tributaries in those regions. Multiyear and more frequent severe droughts, like those in 2005 and 2010, are killing trees that humans don’t cut down as well as increasing the risks of more common fires (both man-made and otherwise).

The trees are also growing fast—faster than expected for a “mature” rainforest—according to a network of measurements.

The exact cause or causes of this accelerated growth—which means the Amazon’s 5 million square kilometers of trees are now Read more…

A river hidden underground has surfaced. Scientists estimate a subterranean river, called Rio Hamza, may be 6,000km long and hundreds of times wider than the Amazon

The territory in Brazil has 20% of freshwater on the planet, but apparently, this number may be even greater. According to the State agency, Researchers at the National Observatory (ON) found evidence of an underground river of 6,000 km in length, which runs down the Amazon River, at a depth of 4000 meters.

The two streams still have the same flow direction, ie from west to east, but its features are quite different.Brazilian scientists have discovered the existence of an underground river about 6,000 kilometers long running 4,000 meters deep Read more…

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BRASILIA — Deforestation in Brazil’s Amazon increased by 15 percent during the past 12 months, the National Institute for Space Research (INPE) said.

From July 2010 to July 2011 the vast South American rainforest lost 2,654 square kilometers (1,649 square miles) of vegetation in the states of Mato Grosso and Para, according to a preliminary analysis of satellite photos.

The year before, 2,295 square kilometers (1,426 square miles) were destroyed over that time period.

This July, 225 square kilometers (139 square miles) were lost to deforestation, though this was significantly less than the 485 square kilometers (301 square miles) destroyed in July 2010.

In April 477 square kilometers (296 square miles) were destroyed, with Read more…